Questions tagged [reference-request]
This tag is used if a reference is needed in a paper or textbook on a specific result.
14,544
questions
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Is the space of Radon measures a Polish space or at least separable?
Background: I work on a SPDE problem where in order to apply Prokhorov's theorem I need that some measure space is Polish space. And additionaly it would be good if that space is Banach space. Earlier ...
11
votes
2
answers
672
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Character theory and Quantum Chemistry
Who (presumably a chemist) realized first the efficiency of character theory in calculations of orbitals of atoms? In which year?
6
votes
0
answers
128
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Generalization of pseudogroups
Pseudogroups are defined here: https://ncatlab.org/nlab/show/pseudogroup
One of the problems with defining manifolds in terms of pseudogroups is that it gives no notion of a morphism between manifolds,...
5
votes
2
answers
695
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What is this disintegration-like theorem?
This is cross-posted at MSE.
I'm looking for a reference for the following result. It seems like it must be known, or follow quickly from something known, but I have not been able to find it in any ...
7
votes
1
answer
482
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Furthest distance half the diameter?
Let $S$ be the surface of a convex body, polyhedral or smooth,
embedded in $\mathbb{R}^3$.
For a point $x \in S$, let $F(x)$ be the set of furthest points
from $x$, measured by shortest paths on the ...
4
votes
0
answers
247
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p cohomological dimension of a profinite group
I would like to know what is the $p$-cohomological dimension of $\textrm{Gal}(\mathbb{Q}_S/\mathbb{Q}_{cyc})$. Here $S$ is a finite set of primes containing $p$ and the Archimedean primes and $\mathbb{...
1
vote
0
answers
154
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Mixed Hodge structures over $F\otimes \mathbb{R}$
Let $F$ be a number field. Nekovàř, on page 18 of Values of L-functions and p-adic cohomology, is referring to the category of mixed Hodge structures over $F\otimes_{\mathbb{Q}} \mathbb{R}$. Can ...
6
votes
1
answer
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Number of irreducible representations of $SO_3(\mathfrak{o}/\mathfrak{p}^l)$
$\DeclareMathOperator\SO{SO}$Let $F$ be a finite extension of $\mathbb{Q}_p$, and let $\mathfrak{o}$ denote the ring of integers, with maximal ideal $\mathfrak{p}$. Let $G_l$ denote the finite group $\...
3
votes
0
answers
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exterior problem for fractional Laplacian
Does there exist a theory of fractional laplacian on exterior domains such as
$$
\ \ \left\{\begin{aligned}
(-\Delta)^{s} u&= 0 &&\text{in } \mathbb R^N\setminus \mathbb B \\
u & ...
6
votes
1
answer
265
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Borel / Wadge hierarchies on subsets closed under prepending a finite prefix
I'm interested in subsets $X$ of the Cantor space ($2^\omega$) or the Baire space ($\omega^\omega$) that are closed under prepending an arbitrary finite prefix:
$$
(x_1, x_2, \dots) \in X \implies (...
4
votes
1
answer
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What about $n^{\frac{1}{x}+\frac{1}{y}}+n^{\frac{1}{y}+\frac{1}{z}}=n^{\frac{1}{z}+\frac{1}{x}}$ over positive integers?
I've considered the following equation for positive integers $x,y,z\geq 1$, and for positive integers $n\geq 2$
$$n^{\frac{1}{x}+\frac{1}{y}}+n^{\frac{1}{y}+\frac{1}{z}}=n^{\frac{1}{z}+\frac{1}{x}},\...
4
votes
1
answer
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Does the Legendre-Fenchel transform/convex conjugate of strongly convex functions have any desirable properties?
It is well known in convex analysis that when a closed, proper, function $f$ is Legendre-type, that is, essentially strictly convex and essentially smooth, the Legendre transform yields a dual ...
17
votes
4
answers
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Differential geometry applied to biology
This was originally a question posted here on MathSE. But I'll ask again here to see if I can get some different answers.
I'm looking for current areas of research which apply techniques from ...
0
votes
0
answers
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What about an alternative formulation for different prime constellations in the spirit of Suzuki's theorem for twin primes?
It is known that the twin prime conjecture is a special case of the $k$-tuple conjecture. See if you want the article with title k-Tuple Conjecture from the encyclopedia Wolfram MathWorld.
On the ...
6
votes
2
answers
404
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Reduction to Lie algebra version of fundamental lemma?
Ngo famously proved the Langlands-Shelstad fundamental lemma for Lie algebras using the geometry of the Hitchin fibration.
For the purposes of the trace formula, one actually needs the fundamental ...
8
votes
0
answers
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A diagram in the proof of Theorem 2.5.5 of 'Cohomology of Number Fields' and the Tate Spectral Sequence
I've been reading the book 'Cohomology of Number Fields' for years.
But I couldn't check the commutativity of the diagram
on page 126 until now. So I ask for help.
The diagram is induced by taking ...
7
votes
0
answers
124
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Removing rows to reduce the rank
What is the smallest number of rows one can delete from a matrix to reduce its rank (by $1$)? Is there any standard name / notation for this characteristic? Has it been studied?
I am in fact ...
7
votes
2
answers
384
views
Is every metric uniformly close to a metric with negative scalar curvature?
Let $M$ be a smooth manifold with non-empty boundary.
Let $g$ be a smooth Riemannian metric on $M$. Is the following true?
For every $\epsilon >0$ there exist a Riemannian metric $g_{\epsilon}$ ...
4
votes
1
answer
173
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Intrinsic volumes of non-polyconvex, non-compact sets
I am reposting this question I asked and bountied on Math SE, which has been upvoted but not answered or commented on.
The intrinsic volumes (AKA Minkowski Functionals or, with different ...
13
votes
3
answers
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Is $\sum_{n=1}^\infty\frac{S(n)}{n!}$ an irrational, where $S(n)$ denotes the sum of remainders function?
For each integer $n\geq 1$ we consider the arithmetic function $$S(n)=\sum_{k=1}^n n\text{ mod }k,\tag{1}$$
the sum of remainders function, the arithmetic function A004125 from the OEIS.
Example. We'...
4
votes
1
answer
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Reference for definition of residue of a differential form, in all characteristics
What is the standard reference for a definition , valid in all characteristics, of the residue in a point of a rational differential form on a curve?
4
votes
0
answers
937
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Next step in studying arithmetic geometry
This relates to this post.
I want to study arithmetic, such as Fermat's last theorem, Faltings' theorem, Mazur's torsion points theorem, Weil conjecture and so on.
For understanding these theorems (...
9
votes
0
answers
788
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How many ways are there to teach class field theory?
I will soon have to teach class field theory (I do not know whether it will be local or global yet:)) to postgraduate students. I wonder, which approaches to this subject(s) exist now.
I definitely ...
3
votes
0
answers
150
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A variant on the Higman-Thompson groups
Let $C = \mathbb{Z}/d\mathbb{Z}$ ($d \ge 0$).
Let $D = \langle a_c : c \in C, t \mid a^2_c = t^d = 1, ta_ct^{-1} = a_{c+1} \rangle$.
let $E$ be the subgroup generated by $\{a_c : c \in C\}$ and let $...
1
vote
1
answer
114
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Reference requence: scheme of complete homomorphisms of rank $r$ via blowups
I'm reading these notes
where it states in section $3$: (transcribed because I can't post image)
Step 1. Introduce the stacks of degenerated and iterated shtukas
which extends that of shtukas.
This ...
0
votes
1
answer
367
views
Reference request: Oldest books on analytic geometry with unsolved exercises?
Per the title, what are some of the oldest books on analytic geometry out there with unsolved exercises? Maybe there are some hidden gems from before the 20th century out there.
7
votes
0
answers
213
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Reference request: retracts are summand inclusions in additive $\infty$-categories
Suppose that $\mathcal{A}$ is an additive $\infty$-category. By this I mean that $\mathcal{A}$ is pointed, semi-additive (i.e., admits biproducts, which I will call direct sums and denote by $\oplus$),...
6
votes
0
answers
123
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Countable-to-one factors of measure preserving systems do not change entropy
It is known that if $\psi$ is a factor map between probability measure preserving systems $(X,\mathscr{X},\mu,T)$ and $(Y,\mathscr{Y},\nu,S)$ is countable-to-one almost everywhere, then $h(\mu,T)=h(\...
0
votes
1
answer
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Inclusion of closed submanifolds of a manifold
Consider a smooth compact manifold $M$ of dimension $n$, with or without boundary. Choose a submanifold $N$ of $M$ of dimension $k$, where $1 \leq k \leq n - 1$, such that $N$ is either without ...
1
vote
1
answer
121
views
Reference request concerning order statistics from the uniform distribution
Let $U_1,\dots,U_n$ be iid random variables uniformly distributed on the interval $[0,1]$, with the corresponding order statistics $U_{(1)}\le\dots\le U_{(n)}$. Let $G_i:=U_{(i+1)}-U_{(i)}$ for $i=0,\...
1
vote
0
answers
86
views
Local coefficient systems in cohomology
Let $\mathcal F$ be a locally constant sheaf with values in $\mathbb C$ on a nice enough space, say a compact manifold. The etale space of $\mathcal F$ defines a covering $p: \tilde X \to X$.
Is ...
13
votes
0
answers
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Is there a slick proof of the fundamental theorem of dimension theory?
The fundamental theorem of dimension theory in commutative algebra states that given a module $M$ over a noetherian local ring $A$, we have $s(M)=\text{dim}(M)=d(M)$ (where $s(M)$ is the infimum of ...
20
votes
2
answers
2k
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Applications of number theory in dynamical systems
I am looking for references (or ways to find references) on significant and/or recent applications of techniques in number theory to problems in the areas of dynamical systems and nonlinear dynamics.
...
2
votes
0
answers
129
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Weak Lefschetz property Jacobian ring smooth hypersurface
Let $A_{.}$ be a graded commutative ring. We say that $A_{.}$ satisfies the weak Lefschetz property if for generic $L \in A_1$ the multiplication maps $ \times L : A_i \longrightarrow A_{i+1}$ has ...
2
votes
0
answers
85
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State-of-the-Art algorithms for bilevel optimization
I want to numerically solve a bilevel optimization problem of the form
$$ \min_y f(y, \hat x(y)), \qquad \hat x(y) = \arg\min_x g(x, y) $$
(for simplicity assume that $\min_x g(x, y)$ exists and is ...
12
votes
2
answers
962
views
Higman's lemma and a manuscript of Erdős and Rado
Motivated by a problem in factorization theory, I've recently proved the following:
Theorem. If $X$ is a non-empty finite alphabet and $\mathcal W$ an infinite subset of the free semigroup, $X^\ast$...
5
votes
1
answer
214
views
Homologous quotient of fundamental groupoid
Let $X$ be a connected space and $\Pi_1(X)$ be its fundamental groupoid. We consider the homologous relation $\mathcal R$ on every morphism space: $f,g\in \Pi_1(X)(p,q)$ are related if the singular ...
3
votes
1
answer
582
views
Simplicity of the first Laplace-Beltrami eigenvalue on Riemannian manifolds
On a compact Riemannian manifold $M$ (we assume Dirichlet boundary condition if $\partial M \neq \emptyset$), the Laplace-Beltrami operator $-\Delta$ has a discrete spectrum $0 < \lambda_1 \leq \...
9
votes
1
answer
294
views
An extrapolation method
I've stumbled upon a method of extrapolation that I haven't seen before.
We are trying to approximate $f(0)$ for a certain function $f$, which we have only measured
at points $x_0, \ldots, x_N$ in ...
3
votes
0
answers
143
views
Upper bound on the geodesic distance in a Lipschitz domain
I was wondering if the following result is true. If yes, could you please suggest a reference. The result seems to have been used at several papers without quoting any reference. Is the proof ...
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votes
1
answer
255
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Is the conjecture $min(A,B) \le rad(ABC)$ new and correct? [closed]
$\DeclareMathOperator\rad{rad}$Conjecture: If $A, B, C$ are positive integers with $\gcd(A, B)=1$, $\gcd(B, C)=1$, and $\gcd(C, A)=1$, and if $A+B=C$, then $\min(A,B) \le \rad(ABC)$.
If the ...
2
votes
2
answers
287
views
Reference request on computational schemes for $\inf_{x\in\Omega^n}\sup_{y\in\mathbb R^n}F(x,y)$
Let $\Omega\subset \mathbb R^d$ be compact, $\rho$ be a density function on $\Omega$ and $p_1,\ldots, p_n\in (0,1)$ be weights satisfying $\int_{\Omega}\rho(z)dz=1=\sum_{k=1}^n p_k$. We consider the ...
2
votes
0
answers
162
views
vanishing of higher algebraic de Rham cohomology and sheaves of differentials for singular curves
I'm looking for some results or references about de Rham cohomology of curves in less-than-optimal cases. The two vanishing results I care about are:
$H^{k}_{\text{dR}}(X) = 0$ for $k>2$, since $H^...
0
votes
0
answers
23
views
A linear map satisfying the given property
Let $A$ and $B$ be two Banach algebras such that $B$ is a Banach $A$-bimodue and $T:A\rightarrow B$ a linear map satisfying
$T(aa')=aT(a')+T(a)a'+T(a)T(a')$ for all $a,a'\in A$.
If the algerba ...
3
votes
0
answers
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$\left< 15\right>^7/15$-womcode construction
In the article Womcodes constructed with projective geometries Frans Merkx constructed several good wom-codes (write-once memory codes, see How to reuse a "write-once" memory by Rivest & Shamir ...
2
votes
2
answers
247
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Reference request on Min-Max theorem
Consider the following min-max problem
$$\inf_{x\in M} \sup_{y\in N} F(x,y),$$
where $F: M\times N\to\mathbb R$ is Lipschitz and $y\mapsto F(x,y)$ is concave for all $x\in M$. Could we derive $\...
3
votes
0
answers
153
views
Using the Hilbert symbol to find nice field extensions
Let $p$ and $q$ be (not necessarily distinct) odd primes and let $F=\mathbb{Q}_p(\mu_q)$. The $q^{th}$ Hilbert symbol induces a non-degenerate alternating form $$(\cdot,\cdot)_q:F^\times/(F^\times)^q\...
6
votes
0
answers
189
views
Which ring spectra are homotopy limits of simpler ones?
Most surely I will tag this by reference request: I am sure very much is known about this question, I am just too ignorant to even guess where to look. What makes me feel especially foolish is the ...
2
votes
0
answers
130
views
Hypersurfaces whose unit normal $N$ satisfies $[N,X] =0$ for every tangent vector field $X$
Let $M$ be a hypersurface of a Riemannian manifold, and assume that $M$ satisfies the following property:
For each $p \in M$, given a unit normal vector field $N$ defined in a neighborhood $U$ of $...
3
votes
1
answer
168
views
Translation to English of Brillouin's analysis of Airy's integral
I am trying to read the following paper by Leon Brillouin (the part on page 16 onwards):
Léon Brillouin, Sur une méthode de calcul approchée de certaines intégrales dite méthode du col, Annales ...